Taming malaria with neem
SCIENTISTS at the Malaria Research Centre (MRC), New Delhi, say neem oil used in low concentrations effectively repels malaria-carrying mosquitoes that are resistant to pesticides.
This is welcome news because malaria has re-emerged as a major public health threat because the malaria-causing microorganism, Plasmodium falciparum, is increasingly resistant to chloroquine -- the primary antimalarial drug. And, the mosquito, Anopheles culcifacies, which transmits 60-70 per cent of the country's 2 million annual malaria cases, has developed resistance to such chemical pesticides as HCH and DDT.
Synthetic pyrethroid impregnated mats and coils are now being increasingly used to repel mosquitoes. However, reports indicate prolonged exposure to these compounds may be harmful to humans.
Keeping this and mosquito resistance in mind, MRC scientists have turned to neem. Says MRC director V P Sharma, "We have discovered that low concentrations of neem oil are extremely effective as cheap mosquito repellents that can easily replace imported pyrethroids."
Recent studies have revealed mats impregnated with 5-10 per cent neem oil are far more effective repellents than mats now in the market. Neem oil mixed with kerosene and burnt in tin lamps also keeps mosquitoes away. Sharma says studies undertaken in Ghaziabad district, where malaria is endemic, showed 1 per cent concentration of neem oil in kerosene was enough to provide complete protection from Anopheles mosquitoes without any eye irritation, cough or respiratory problems, because neem oil's normally strong odour is absent at low concentrations. "As kerosene is a commonly used lighting fuel," Sharma adds, "it could easily be fortified with neem oil, which would provide protection especially in the far-flung areas of the country."
Scientists have also found a mixture of 2 per cent neem oil in coconut oil, when applied to the body, provides complete protection for about 12 hours from all Anopheles species and from sandflies (Phlebotomus argentipes) that transmit kala-azar, rampant especially in parts of Bihar.
MRC studies indicate neem oil-based repellents are much cheaper than those available in the market. Neem oil mats provide protection for a year at a cost of Rs 56, compared to Rs 494 for commercially produced, pyrethroid-impregnated mats. No wonder Sharma stresses, "It is essential that more and more people become aware of this simple and safe technology, as it could go a long way in dealing with the almost uncontrollable malaria problem."